Punctures in the tread area of a car tyre can often be repaired if the driver hasn’t driven too far on it.
Some car makers supply a tyre sealant and inflator pack instead of a spare wheel. The sealant and compressed gas are injected through the tyre valve. However the result will depend on the cause of the puncture and the distance travelled on the deflated tyre.
There are two basic types of sealant.
These are put into the tyre as a preventative measure either at the time the tyres are fitted or by injection through the tyre valve. The aim is to prevent air loss if a puncture does occur so the driver can continue the journey without interruption.
The seal is pretty much instantaneous after the tyre has been punctured. The concern with this is that the driver will have no idea whether there's been a puncture or not. A large screw or nail in the tread of the tyre will cause further damage over time and could lead to more serious problems.
These are used following a puncture. The sealant and compressed gas to re-inflate the tyre are applied through the valve. Carrying a can of tyre sealant can bring peace of mind if you regularly drive alone, but it is vitally important that you spot the puncture early and stop quickly. Running in a partially or fully deflated condition will cause weakening of the tyre structure and irreparable damage.
Permanent or temporary?
Advice from tyre experts to users of pre-puncture sealants is to inspect the tyres VERY often, i.e. Every time you use the vehicle. If the pre-puncture sealant has been activated there should be signs of the sealant (usually white latex based) on the outside of the tyre. If there are any signs of this or of a penetrating object, then the tyre must be removed from the rim and properly inspected to see if it is suitable for permanent repair.